Plants are the greatest carbon dioxide sinks on earth. They convert atmospheric CO2 with the help of sunlight into biomass. Plants grow poorly at temperatures even modestly higher than their optimum growth temperature (5-10° C.) utilizing CO2 less efficiently. A recent study reported that global warming (associated with higher CO2 in the atmosphere) already adversely affects harvest yields of food crops such as maize and wheat. Lobell et al. Climate trends and global crop production since 1980. Science, 5 May 2011. DOI: 10.1126/science.1204531. Consequently, heat stable plants are required to maintain food security in light of climate change. Indeed, global average temperatures are expected to rise even further; therefore, it is an essential problem to solve.
Rubisco is an enzyme that catalyzes the first step in carbon fixation utilizing atmospheric CO2 and is found in all photosynthetic bacteria, algae and plants. Rubisco requires another enzyme, rubisco activase, for activation.
While rubisco is a fairly heat stable protein, the rubisco activase is not. It is well established that the inhibition of CO2 assimilation and net photosynthesis (affecting plant growth) is due to thermal instability of rubisco activase. Thus, there exists a need in the art for a heat stable rubisco activase.